WASHINGTON -- As the nation's spy agencies assess the fallout from disclosures about their surveillance programs, some government analysts and senior officials have made a startling finding: The impact of a leaked terrorist plot by al-Qaida in August has caused more immediate damage to U.S. counterterrorism efforts than the thousands of classified documents disclosed by Edward Snowden, the former National Security Agency contractor.
Since news reports in early August revealed that the United States intercepted messages between Ayman al-Zawahri, who succeeded Osama bin Laden as the head of al-Qaida, and Nasser al-Wuhayshi, the head of the Yemen-based al-Qaida in the Arabian Peninsula, discussing an imminent terrorist attack, analysts have detected a sharp drop in the terrorists' use of a major communications channel that authorities were monitoring. Since August, senior U.S. officials have been scrambling to find new ways to tap into the electronic messages and conversations of al-Qaida's leaders and operatives.
"The switches weren't turned off, but there has been a real decrease in quality" of communications, said one U.S. official, who like others quoted spoke on the condition of anonymity.
The drop in message traffic after the communication intercepts contrasts with what analysts describe as a far more muted impact on counterterrorism efforts from the disclosures by Mr. Snowden of the broad capabilities of NSA surveillance programs. Instead of terrorists moving away from electronic communications after those disclosures, analysts have detected terrorists mainly talking about the information that Mr. Snowden has disclosed.
Senior U.S. officials say Mr. Snowden's disclosures have had a broader impact on national security in general, including counterterrorism efforts. This includes fears that Russia and China now have more technical details about the NSA surveillance programs, as well as damaged diplomatic ties, like the decision by Brazil's president, Dilma Rousseff, to postpone a state visit to the United States in protest over revelations that the agency spied on her, her top aides and Brazil's largest company, the oil giant Petrobras.
The communication intercepts between Mr. Zawahri and Mr. Wuhayshi revealed what U.S. intelligence officials and lawmakers have described as one of the most serious plots against American and Western interests since 9/11. It prompted the closure of 19 U.S. Embassies and consulates for a week, when the authorities ultimately concluded that the plot focused on the embassy in Yemen.
McClatchy Newspapers first reported on the conversations between Mr. Zawahri and Mr. Wuhayshi on Aug. 4. Two days before that, The New York Times agreed to withhold the identities of the al-Qaida leaders after senior U.S. intelligence officials said the information could jeopardize their operations. After the government became aware of the McClatchy article, it dropped its objections to The Times' publishing the same information, and the newspaper did so on Aug. 5.
U.S. counterterrorism officials say they believe the disclosure about the al-Qaida plot has had a significant impact because it was a specific event that signaled to terrorists that a main communication network that the group's leaders were using was being monitored. The disclosures from Mr. Snowden have not had such specificity about terrorist communications networks that the government is monitoring, they said.
Other senior intelligence and counterterrorism officials offer a dissenting view, saying it is difficult, if not impossible, to separate the impact of the messages between the al-Qaida leaders from Mr. Snowden's overall disclosures.nation